Tiger Global Management, the $15 billion investment firm that has invested in the likes of the Alibaba Group and the sunglasses maker Warby Parker, has begun raising a $1.5 billion fund, just five months after raising another $1.5 billion vehicle, a person briefed on the matter said on Tuesday.

The new fund will be dedicated to private equity and venture capital opportunities, the kind of investments that have made Tiger Global one of the better-known Wall Street backers of popular start-ups.

Founded in 2005 with the backing of the hedge fund magnate Julian H. Robertson of Tiger Management — and earning the sobriquet “Tiger cub” in the process — the firm began life as a hedge fund. But its business of investing in private companies, led by Lee Fixel and Scott Shleifer, has since eclipsed its original operation, accounting for more than half of the $15 billion in Tiger Global’s assets under management.

Sometimes the firm’s investments have taken on unusual forms. It led a round of financing in Harry’s, a shaving company, meant principally to help the start-up buy a nearly 100-year-old German razor blade manufacturing plant.

Among the ways that the firm has stood out from other Wall Street investors is its willingness to venture into other countries for investment opportunities. Its portfolio includes stakes in Flipkart, a big Indian online shopping company, and Quikr, an Indian online classifieds site. And it bought shares in Alibaba, the Chinese e-commerce juggernaut that went public last week, through the secondary market last year.

A spokeswoman for Tiger Global declined to comment on the fund-raising, which was reported earlier by Fortune.

A version of this article appears in print on 09/24/2014, on page B9 of the NewYork edition with the headline: New Tiger Fund.